Method and apparatus for cleaning the interior of a tank



July 4, 1961 c. IN 'T VELD ETAL 2,991,203

METHOD AND APPARATUS FOR CLEANING THE INTERIOR OR A TANK July 4, 1961 C,|N T VELD ETAL 2,991,203

METHOD AND APPARATUS FOR CLEANING THE INTERIOR OF A TANK Filed OGt. 28,1958 3 Sheets-Sheet 2 INVENTORS Comvs L1 s :Uv T VELD BY Taunumislv VELDA Trozw e' y July 4, 1961- c. 1N 'T VELD ETAL 2,991,203

METHOD AND APPARATUS FOR CLEANING THE INTERIOR OF' A TANK Filed Oct. 28,1958 3 Sheets-Sheet 5 ATTORNEY United States Patent O 2,991,203 METHODAND APPARATUS FOR CLEANING THE INTERIOR OF A TANK Cornelis in t Veld, 12Burg. Luijerinksingel, and J0- lrannes in t Veld, 13 Burg.Luijerinksingel, both of Vlaardingen, Netherlands Filed Oct. 28, 1958,Ser. No. 770,168 Claims priority, application Netherlands Oct. 31, 19577 Claims. l(Cl. 134-24) The invention-concerns a method and an apparatusfor cleaning the interior of a tank of, for instance, a tanker, a shoreinstallation or the like, according to which a cleaning liquid isejected from nozzles which are rotatable about a horizontal transverseaxis, said nozzles forming part of an apparatus which itself isrotatable about a vertical axis. A similar method and apparatus areknown from the Dutch patent specification No. 32,888, according to whichtwo nozzles rotating in parallel vertical planes about a horizontal axisperform at the same time a movement about a vertical axis of rotation.In this treatment the cleaning liquid is delivered inv equal quantitiestowards the top and the bottom. Because the body of revolution of theserotating nozzles here described with each revolution has as points ofintersection the points perpendicularly below and above the apparatus,relatively large quantities of liquid are sprayed on and about thesepoints of intersection. In such tanks, however, the largest amount ofdirt isto be found on the lower part of the side-walls of the tank andin the corners, in particular the lower corners near the bottom, towardswhich parts relatively small quantities of cleaning liquid are sprayedby the known method. The cleaning liquid usually employed is hot waterunder a pressure of about l2 atm. QuantitiesV ofabout 80 tons/hour ,are

ice

- adjustment where the jets act in the corners of Ithe tank,

- to be entirely adjusted to the dirtiest place, so that too requiredfor this, and it will be Yevident that such a quantity of hot waterunder high pressure is an expensive liquid, for the production of whichaygood deal of power is needed. If the cleaning of the tanks of asteam-driven tanker has to be carried out during navigation, the amountof power required for thisis frequently j so great that the tankercannot sail on normally, but has zzo reduce its speed considerably. j

Now the invention has for its object to furnish a method and apparatusby means of Vwhich it is possible to carry out the cleaning of a tank ina way which is more eiiicient and also involves a saving of liquid.

` According to the invention this object is achieved by the fact thatfor the duration of one cycle of treatment the nozzles, performing agiven number of revolutions about the vertical axis, are simultaneouslyadjusted only once'from the top to the bottom. Whilst thereforeaccording to the known methods the jets act upon the Walls of the tankaccordingto curved lines extending side by side from the top to thebottom, in accordance with the invention the action upon the walls takesplace according to a spiral line on the top and bottom surfaces andaccording to helical lines on the side-walls of the tank. According tothe invention it is possible to control the nozzles in such a way duringtheir adjustment about the horizontal axis that the action of the jetsis shorter on those surfaces which are less dirty and longer on thosewhich are dirtier. According to theinvention the adjustment of thenozzles about the horizontal axis may therefore take place withvaryingspeed, a slower adjustment in particular taking place in those ranges ofmuch cleaning liquid is sprayed in all other less dirty places. Thisexcessive use of cleaning liquid can be avoided by the method accordingto the invention because in consequence of a ready adjustment of thenozzles the jets can move quickly over the less dirty surfaces andaccording to the inventionthe adjustment in the corners takes place moreslowly, In fact, in these corners greater demands are made on thecleaning in connection with the Irelative increase of the area to becleaned and the presence of additional surfaces, connected with theconstruction of the tank.

- Further it is no longer necessary to use the same nozzle in the upperrange of the tank and in the lower range, so that nozzles of differentdiameters can be employed for theseranges, which involves a furthersaving of` cleaning liquid. Even apart from the better cleaning in thecorners which is possible `with the method according to the invention, asaving of about 3,000.- is obtained during the cleaning of a tanker, sothat the cost of the apparatus for carrying out the method is alreadyamply Irecovered in one treatment. v

The apparatus for carrying out the method according to the invention maybe formed by a casing adapted to rotate about a -vertical axis relativeto its suspension through which casing the cleaning liquid is fed, whileon the outside it is iitted with one or more nozzles'rotatable about ahorizontal transverse axis, which nozzles are connected with means foradjusting these nozzles. In order to obtain different quantities ofliquid for the treatment of the upper and the lower part of a tankrespectively, according to the invention near each horizontal transverseaxis two nozzles connected with each other and with the operating meansmay be provided, which nozzles include an angle of about with each otherand can be adjusted over a corresponding angular range. The nozzle whichthen covers the upper part of the-tank may have a smaller outlet openingthan the other nozzle.

According to the invention each nozzle or each set of nozzles may beconnected with a vertically adjustable body engaging the helical threadsof a member-driven so as to rotate about a vertical axis, the helicalthreads of said member, which bring about the downwardr vadjustment ofthe nozzles, having a variable pitch, while further a return thread witha considerably greater pitch running in the opposite direction ispresent. The helical threads of dilferent pitch cause the nozzles ingiven ranges to be adjusted more slowly than in other ranges, while atthe end of thecycle an accelerated return to a new starting positiontakes place. Owing to this variable pitch the nozzles can move morequickly over the upper side and lower surfaces of the tank and act for alonger time upon the angular ranges of the tank. 'q l According to theinvention, in the casing there may be mounted a turbine driven by theflow of the liquid,l which turbine drives, via a reduction gear, thecasing rotating about the vertical axis and also, via a second reductiongear, the member provided with helical threads.'` This type of driveprovides for the rotation about 'the vertical axis of rotation and forthe slow adjustmentof the nozzles about the horizontal axis as well asthe readjustment to the new starting position, upon which the cycle maybe repeated again, if necessary.

The invention will now be explained more fully with reference to thedrawings, which illustrate an embodiment of the apparatus for carryingout the method according to the invention.

-FIGURE 1 is a vertical cross-section of the apparatus according to theinvention.

FIGURE 2 is a horizontal cross-section along the line -II-II in FIGURE1.

FIGURE 3 is a horizontal cross-section along the line III- III in FIGUREl.

FIGURE 4 is a cross-section of a part of FIGURE 3 along the line IVIV.

FIGURE 5 is a vertical section on a smaller scale of a tank and cleaningapparatus embodying the invention.

The apparatus shown inthe drawings consists. of a protective protectivecap and handle 1, a casing 2, which is provided with a connection (notshown) for feeding cleaning liquid to the interior 3 of said casing. Onthis casing 2, which is stationary during the operation of theapparatus, via a ball bearing 4 the casing 5 of the apparatus isrotatably suspended.

Near the lower end this casing 5 is constructed to have rubber-linedlaterally extending lugs 6, near which a sleeve 7 is rotatablysupported, from which sleeve extend two nozzles 8 and 9 respectively,which nozzles practically include an angle of 90 with each other, butare placed the former at a small angle inwards towards the vertical andthe latter at a small angle upwards towards the horizontal. This isnecessary in order to prevent certain sur.l faces not being sprayed andto obtain overlapping.

The casing 5 is closed at the bottom by a cover 10, on which are fixedcolumns 11 directed vertically upwards. These columns 11 serve as guidesfor blocks 12 movable along them, which blocks are fitted with stubaxles 13, arms 14 extending into bushings 15 of the sleeve 7, rotatableabout a horizontal transverse axis, being supported on said stub axles.When the blocks 12 are moved upwards along the columns 11, the rods 14will move in the bushings 15, with the simultaneous rotation of thesleeve 7 and consequently of the nozzles 8 and 9. The blocks 12 arefitted with a member 16 meshing with a helical thread of a member 17rotatable afbout a vertical axis. The helical threads of this member 17have a variable pitch, in the sense that the pitch is greater at thelower and the upper ends where the nozzles are in registration with theat wall surfaces than in the central section where the nozzles are inregistration with the more remote corner sections of the tank. Thereturn thread 17b is of greater pitch than the thread 17a so that thenozzles are returned at a more rapid rate for repeating the cycle.

Both the casing 5 and the member 17 tted with threads are power-driven,for which purpose in the upper part of the casing 2 a turbine 18 ismounted, which drives a shaft 19 supported in the innermost .part of thecasing. This shaft 19 carries a worm screw 20, also shown in FIGURE 2,and this worm screw drives a worm wheel 21 of a shaft 22, on which asecond worm 23 is mounted. This worm 23 meshes with a worm wheel 24 of ashaft 25, at the upper end of which is located a gear wheel 26 meshingwith an internal gear 27 of the casing 5. In this way the casing S isdriven with great reduction, so that it rotates about the vertical axisand thus also im parts a similar rotation to the nozzles. At the lowerend of the shaft 25 is located a second gear wheel 28, also meshing withan internal gear 29, which is connected with the member 17 tted withhelical threads, by which means the latter is driven. This drive resultsin the upward movement of the blocks 12 and accordingly` in the rotationof the nozzles.

'Ihe cleaning liquid ows through the hollow interior of the casings 2and 5, and can enter via the ends of the sleeve 7 into the interior ofthe latter and leave it via the nozzles fitted on the sleeve. To thisend the bushings at the ends near the guide bushing 15 for the rod 1-4are shaped in the way indicated in FIGURE 4. The nozzles are adjustedover an angle which is slightly greater than so that sufficientoverlapping is obtained.

It will be evident that instead of the driving mechanism for theadjustment of the nozzles it is also possible to use other mechanisms oreven manual operation, by means of which the adjustment is effected byhand in a simple way, from the top.

It is further to be noted that after each cycle of treatment the nextcycle starts in another point, so that upon repetition of the treatmentthe lines described on the walls differ from those of the precedingcycle.

The apparatus above described is shown in FIG. 5 as positioned forcleaning a tank having a top wall 30 provided with an opening 31 throughwhich the apparatus is inserted and having side walls 32 and a bottomwall 33. 'Ihe nozzles are so disposed that one set of nozzles cleans thetop wall 30 and the upper portion of the side wall 32, while the otherset of nozzles cleans the lower portion of the side wall 32 and thebottom wall 33.

What we claim is:

1. The method of cleaning deposits from the interior walls of a tank orthe like having top, bottom and side walls, which comprises sprayingonto the interior surfaces of said walls a cleaning liquid from aplurality of nozzles within said tank, said nozzles extending normal toa horizontal axis and being spaced laterally from a given vertical axiswhile rotating said set of nozzles about said vertical axis at a uniformrate and simultaneously oscillating said nozzles about said horizontalaxis in such an arc that liquid from certain of said nozzles impinges onthe top and upper side walls of said tank and liquid from others of saidnozzles impinges on the bottom and lower side walls of said tank anddischarging a larger quantity of said liquid from the last mentionednozzles than from the iirst mentioned nozzles to compensate for thegreater quantity of deposit to be removed from the lower portion of saidwalls.

2. The method set lforth in claim 1 in which said nozzles are arrangedin pairs displaced relatively by about 90 with respect to saidhorizontal axis and are oseillated in an arc of the order of 90.

3. Apparatus for cleaning deposits from the interior surfaces of a tankor the like having top, bottom and side walls, comprising a casing -tobe disposed within said tank and mounted to rotate about a verticalaxis, a plurality of sets of nozzles mounted on said casing to beoscillated about horizontal axes, said nozzles extending normal to saidhorizontal axes and being displaced from said vertical axis, means foroscillating certain nozzles of each set in an arc adapted to cause theliquid therefrom to contact the top and upper side walls only of saidtank and means for oscillating other nozzles of each set in an arcadapted to cause the liquid therefrom to contact the bottom and lowerside walls only of said tank, and means simultaneously rotating saidcasing about said ver. tical axis for thereby causing said liquid tocontact said walls around the entire periphery of said tank.

4. An apparatus as set forth in claim 3 in which said last mentionednozzles are adapted to discharge a greater quantity of liquid than saidtirst mentioned nozzles to compensate for the greater quantity ofdeposit to be removed from the lower portion of said walls.

5. An apparatus as set forth in claim 3 in which said nozzles arearranged in pairs, the nozzles of each pair being relatively displacedby about 90 with respect to said horizontal axes and wherein means isprovided to cause said nozzles to oscillate about said horizontal axesthrough an arc of the order of 90.

6. An apparatus as set forth in claim 5 wherein means is provided tocause the nozzles to oscillate at a greater rate at the extremities oftheir path of travel than at the center portion of their path of travel.

7. An apparatus as set forth in claim 3 wherein said means foroscillating said nozzles includes 4means to -feed said nozzlesdownwardly at a predetermined rate and means for returning said nozzlesupwardly at a predetermined faster rate.

References Cited in the file of this patent UNITED STATES PATENTSFranklin Iuly 19, 1892 Morse June 24, 1919 Butterworth May 26, 1931Lewis Oct. 24, 1939 Kennedy July 26, 1955 Scruggs July 23, 1957

1. THE METHOD OF CLEANING DEPOSITS FROM THE INTERIOR WALLS OF A TANK ORTHE LIKE HAVING TOP, BOTTOM AND SIDE WALLS, WHICH COMPRISES SPRAYINGONTO THE INTERIOR SURFACES OF SAID WALLS A CLEANING LIQUID FORM APLURALITY OF NOZZLES WITHIN SAID TANK, SAID NOZZLES EXTENDING NORMAL TOA HORIZONTAL AXIS AND BEING SPACED LATERALLY FROM A GIVEN VERTICAL AXISWHILE ROTATING SAID SET OF NOZZLES ABOUT SAID VERTICAL AXIS AT A UNIFORMRATE AND SIMULTANEOUSLY OSCILLATING SAID NOZZLES ABOUT SAID HORIZONTALAXIS IN SUCH AN ARC THAT LIQUID FROM CERTAIN OF SAID NOZZLES IMPINGES ONTHE TOP AND UPPER SIDE WALLS OF SAID TANK AND LIQUID FROM OTHERS OF SAIDNOZZLES IMPINGES ON THE BOTTOM AND LOWER SIDE WALLS OF SAID TANK ANDDISCHARGING A LARGER QUANTITY OF SAID LIQUID FROM THE LAST MENTIONEDNOZZLES THAN FROM THE FIRST MENTIONED NOZZLES TO COMPENSATE FOR THEGREATER-QUANTITY OF DEPOSIT TO BE REMOVED FROM THE LOWER PORTION OF SAIDWALLS.
 3. APPARATUS FOR CLEANING DEPOSITS FROM THE INTERIOR SURFACES OFA TANK OR THE LIKE HAVING TOP, BOTTOM AND SIDE WALLS, COMPRISING ACASING TO BE DISPOSED WITHIN SAID TANK AND MOUNTED TO ROTATE ABOUT AVERTICAL AXIS, A PLURALITY OF SETS OF NOZZLES MOUNTED ON SAID CASING TOBE OSCILLATED ABOUT HORIZONTAL AXES, SAID NOZZLES EXTENDING NORMAL TOSAID HORIZONTAL AXES AND BEING DISPLACED FROM SAID VERTICAL AXIS, MEANSFOR OSCILLATING CERTAIN NOZZLES OF EACH SET IN AN ARC ADAPTED TO CAUSETHE LIQUID THEREFROM TO CONTACT THE TOP AND UPPER SIDE WALLS ONLY OFSAID TANK AND MEANS FOR OSCILLATING OTHER NOZZLES OF EACH SET IN AN ARCADAPTED TO CAUSE THE LIQUID THEREFROM TO CONTACT THE BOTTOM AND LOWERSIDE WALLS ONLY OF SAID TANK, AND MEANS SIMULTANEOUSLY ROTATING SAIDCASING ABOUT SAID VERTICAL AXIS FOR THEREBY CAUSING SAID LIQUID TOCONTACT SAID WALLS AROUND THE ENTIRE PERIPHERY OF SAID TANK.